Power transmission



Ap 27, 1954 E. F. KLESSIG AL 2,676,466

POWER TRANSMISSION Original Filed May 2, 1950 3 She ats-Sheet l P N NINVENTOR. ERNST F. KLESSIG BY .GLENN M.JONES @KZLM ATTGRNEY A ril 27.1954 Original Filed May 2, 1950 E. F. KLEYSSIG E'T'AL' POWERTRANSMISSION 3 Sheets-Sheet 2 INVENTOR.

ERNST F. KLESSIG BY GLENN M. JONES m K M ATTORNEY Patented Apr. 27, 1954UNITED STATES "FF 112C Farmington, Mich, assignors'to; Vickers lpcorporated, Detroit, Mich, a; corporation of,

Michigan Original application May 2, 1950, Serial- No 159,492. Dividedand this application Novemher 8', 1952, Serial No. 319,524.

10 Claims. 1

This invention relates topower transmissions and is particularlyapplicableto those ofthe type comprising two or more fluid pressureenergy translating devices, one. of which may function as a pump andanother as a fluid motor.

The present application. constitutes a division of the copendingapplication of ErnstF. Klessig: and Glenn M. Jones filcdunder SerialNumber 1'59A92'on May 1950, now abandoned, in; which a powertransmission of the above type; is disclosed.

The invention is generally concerned with-hye draulic power.transmission systemsfor simulta; neously operating a pair of loaddevices ahdin particular with a transmission system which willalsouoperate the pair of load devicesincontinuous reversing cycles.

In general, one embodiment of theihve tion comprises a hydraulictransmission system having-a pressure fluid source anda pair ofreversible fluid motors which are adapted to be; separately associatedwitha pair-of load devices for driving thesame. The motors may be of thecylinderreciprocating piston type having two ports which alternate asinlet and outlet ports for thedelivery of pressure lluidto and-theexhaust of fluid from opposite sides of thepiston. A circuit isvprovided wherein aportof' one of the motors is continuously connected tothe pressure fluid source while the other port of said motor; is con,-vnected in a closed'or series relationship to one oftheports of the othermotor.

The lattermotor has a greater (or lesser) fluid. displacement in onedirection of operation than the displacement of the first motor ineither direction of operation. Automatically operated controlvalve meansis connectedto the remain.- ing port of the latter motor to alternatelyconmeet the remaining port of said motor to.- the pressure fluidsourcecr to exhaust. Valve-means may also be provided for selectivelycontrolling thespeed of the motors and for stopping the motors. Theinvention in its preierredform utilizes control means which will stopthe motors at one. end of their. stroke rather than at.sourcintermediate stage of their operation,

Oneadaptationior the system is for operatingthowindshleld wipers ofvehiclessuchas trucks;

and busses. The system may be economically installed on such vehicles asa branch circuitof a: hydraulic system including a pressure fluid sourcewhich operates, for example, the brakes and doors of theyehicle.

It is therefore. an object of the invention to provide a hydraulictransmission; system for driv l a hydraulic transmissionsystem as abovestated;

which inctudes means for selectively operating the pair of motors incontinuous reversing cycles, for controlling the speed qflt'nemotors,and-for stopping the motorsatone end of their strokes rather thanat an intermediate stage of their lmkfi i Itis a further object of thisinvention to provide a ovel pilot valve operated directional controlvalve of the differential area fluid actuate pe- It is still anotherobjector this inventionto provide adirectional control valve of theabove type which is controlled by apilot valve telescopifihlly mounted;within th directional con rol v lve Further objects and advantages ofthe present invention will be; apparent from the following description;reference being had to the accompanyingdrawings wherein a preferred formor" the present invention is clearly shown.

In the drawings:

Figure 1 is a diagrammatic view of a hydraulic power transmission systemincorporating in section directional control valve mechanism and a pairof reversible fluidmotors, the parts in section being taken on lines, llof Figures 2, 3 and 5V Figure 2 is a right end view of the upper fluidmotor shown in Figure l. s

Figure 3 is a right end view of the lower fluid motor show; in Figure 1.

Figure 4 is a plan view of the upper motor shown in Figure, 1.

Figure 5 is a sectional view of the directional control valveshown inthe upper left portion of Figure 1,

Figure 6 is a view taken on line 5- -5 of the upper fluid motor shown inFigure 1.

Figure '7 is a view taken ou line l] of the upper fluid motor shown inFigure 1.

Figure 8 is aview talgen on line 8-3 of the upper fluid motor showninFigure l.

Eieureih a y iek n n of Figure 3g.of;the body or the lowelmfluidmotorshown in Figure 1.

F u e. ll s: a View; when. L. ine. lflr-l of hei owet flu d, i rsh w o IFi i fev '1 is a ectional,- view aken calm r amiss 3 ll-| l of thecontrol piston of the directional control valve shown in the upper leftportion of Figure 1.

Referring to Figure 1 there is shown a hydraulic power transmissionsystem comprising a pump driven by a prime mover, not shown, andconnected to a fluid tank l2 by a supply conduit l4 and connected by apressure delivery conduit is to an inlet port [8 of a manually operated,rotary control valve 20. Incorporated in the pressure delivery conduitI6 is a pressurerelief valve 22 and an unloading valve 24, both of whichmay be of the conventional type. The unloading valve 24 will bypass thecomplete delivery of the pump to the tank 12 by means of a tank conduit26 whenever a predetermined pressure arises in an accumulator 28 whichis connected to the pressure delivery conduit [3 by means of a branchconduit 30. A conduit 32, also connected to the pressure deliveryconduit I6, may be utilized for delivery of pressure fluid to anotherpart of the transmission (not shown) for operation of other loaddevices.

The relief valve 22 is provided as a safety element in case theunloading valve fails to operate satisfactorily, and will operate in theconventional manner to bypass pressure fluid from the pump Ii) at ahigher predetermined pressure than that of the unloading valve.

In addition to the pressure port l8 the control valve 25, also shown inFigures and 11, is pro vided with two motor ports 34 and 3G and a tankport 38. When a piston 40 of the valve 2!), which is manually rotatableby a control knob 42, is in the position shown in Figure l, the pressuredelivery port [8 is connected to both of the motor ports 34 and 36 Whilethe tank port 38 is blocked from communication with all other ports.When the control knob is rotated 90 the pressure port 18 is connected tothe motor port 34 while the motor port 36 is connected to the tank port38. This is accomplished by means of a transverse passage 43 extendingcompletely through the piston connected to which is a radial passage 44leading to the periphery of the piston, and by means of another radialpassage 46 connected to a longitudinal passage 48, the latter of whichextends to the end of the piston 40 opposite the control knob 42, andwhich is in alignment with and leads to the tank port 38. In theposition shown in Figure 1, the transverse passage 43 connects thepressure port [8 to the motor port 36, and the radial passage 44, incooperation with the transverse passage 43, connects the motor port 34to the pressure port IS.

The radial passage 44 and the transverse passage 43 at one end thereofare provided with enlarged slots indicated by the numerals 49 and 5| atthe periphery of the piston. In addition, a narrow slot, indicated bythe numeral 53, is provided at the periphery of the piston at the otherend of the transvers passage 43 which, when the control valve is inoperating position, is adapted to control the speed of a pair of fluidmotors to which the motor ports are connected. When the control valve isrotated to operating position, the enlarged slots come into registrywith the motor ports just before the metering slot comes into contactwith the pressure port. The pressure port may be selectively openedpartially or fully to the motor ports in order to control the speed ofthe motors.

The tank 38 is connected to the tank [2 by a conduit 50. The motor port34 of the control valve 20 is connected by a conduit 52 to a port 54located at one end of a reversible fluid motor 56 of the oppositelyacting expansible chamber type and having a piston 58 reciprocablymounted within a longitudinal bore 60. The opposite end of the motor 56is provided with a port 62 which is connected by a conduit 63 to a port64 located at one end of a second reversible fluid motor 66 of the sametype as motor 56 and having a piston ea reciprocably mounted within alongitudinal stepped ore 10. The second motor 66 is provided with a port12 near its opposite end which is controlled by valve mechanism to belater described. The opposing faces or pressure effective surface areasof the piston 58 of the motor 5'6, and which are indicated by thenumerals l4 and "IE, are substantially equal while the opposing endfaces or pressure effective surface areas of the piston 68 of the motor65, and which are indicated by the numerals l8 and 88, are unequal. Dueto the fact that the right end of the piston 68 is slightly hollow, thehollow section being indicated by the numeral 8|, the pressure effectivesurface area 18 comprises the end surface of the piston surrounding thehollow section and the end wall at the termination of the hollowsection, the total area being equivalent to the area of the enlargedsection of the bore. It is preferred that the surface area of the piston68 be substantially equal to the surface areas 14 and T6 of the piston58, and that the surface area it of the piston 68 be substantiallylarger. than the surface areas 14 and 16 of the piston 58. In thismanner, because of the differential piston effective surface areas, or,stated in another manner because of the larger fluid displacement of themotor 66 in one direction of operation, when the left and right endsurface areas 1'6 and 18 of the pistons 53 and 68 are simultaneouslyexposed to the pressure fluid source, the motor 66 will. be operated ina leftward directional movement and the displacement from said motorwill operate the motor 56 in a leftward directional movement. When thepiston is in its complete rightward position, the enlarged portion ofthe piston closes the port 12. Thus provision has been made forinitially shifting the piston leftwardly by means of a plurality oftransverse ports 83 in the enlarged section of the piston leading to thehollow section 8|. Pressure fluid is conducted from the port 12 to thehollow section 8| and the end face of the piston through the medium ofthe ports 63 until th end face of the piston breaks over the port "52and the piston is then fluid operated leftwardly by the introduction ofpressure fluid to the right end of the bore 10 through the port 12. Thepistons 58 and 68 are respectively provided with gear racks 82 and 84,the latter of which are respectively adapted to rotate pinion gears 86and 8B in mesh therewith so as to operate, for example, windshield wiperblades (not shown) which may be suitably fastened to shaft stems 9t and92 (Figures 8 and 10) associated with the pinion gears 86 and 88 andextending from the motors 56 and 66.

During operation, as the pistons are hydraulically recip-rocated, thepinion gears in mesh with the piston gear racks will be rotated and theshaft stems will also be rotated so that wiper blades (not shown)fastened tothe stems will be operated in a swinging arc.

As shown in Figures 8 and 10 the pinion gears 86 and 88 are respectivelymounted in stepped bores indicated by the numerals 93 and 95 extendingfrom the front sides of the motors, 55 and 66. The stepped bores 93 and95 are closed,

respectively, by closure-members 91- and'B-Q'Which also serve asmountingboxes through which the duit 33- connected to the port ldl andto-the.10

tank conduit fill-(Figure l and 10);

Referring toFigu'res 1, 6; and 7-, for the purpose of'causing themotorsto be automatically operatedin unison, and in continuous;reversingcycles, there is provided telescopically arrangedvalvularmechanism associated withthe motor 58 comprising a piston pilot valve 94adapted to be operated by the motor 56 and which reciprocates' within abore Hi5- of a fluid operated sleeve'valve' 96 The pilot valve S4 isadapted to be operated near the end of each stroke of the motor 66whichcauses hydraulic operation of the sleeve valve 9B--in reversingcycles so as to connect the port 12; which is near the right end of-thepiston 68 of the motor 66 alternately to th pressure fluid source and tothe tank.

The valvular mechanism may be mounted within and-arranged as an integralpart of the motor 66. For this purpose, the body 98 of the motor 66 isprovided with a longitudinal stepped bore Hill; the open end of which isclosed by an end plate Hi2 which also closes the bore 19 with in whichthe motor piston 63 is mounted. An externally located pressureport ltdis connected to the enlarged portion of the stepped bore lfiil by apressure passage Hi6,- and an externally located tank port IllS isconnected to the smaller portion of the bore lilfiby a passage lid.

The pressure port Hill is connected to the motor part 3% of the rotarcontrol valve Ell-by a conduit lll and'the tank port [Otis connected tothe tank i2 by a conduit H3. Any leakage from the gear rack and pinionarrangement of the motor 68 is provided for by connecting the steppedbore d5; within which the pinion gear 83 is mounted, directly to thesmaller portion of the stepped bore iiiilwith'in which one end of thepiston valve 94 extends and to which the tank passage 1 i6 is connected,the latter being connected to tank l2 by means of the conduit I E3.

The tank passage Ht is in continual com- 4 munication with the'lei't endof bore Hlil, but, however, with the sleeve valve 96 mounted in thelarge end of the bore Hid-the pressure passage IDS is closed fromcommunication with the bore Hi except by the medium of a plurality oftransverse ports H2 in the sleeve extending from the outer peripherythereof and-opening into the central bore [85 within which the pis-= tonvalve 94 is located.

The piston valve M is provided with a long land [M extending from theleft end thereof to the central portion of the piston which permitscontinual communication between the pressure passage its, the bore its,and the sleevev ports H2.- The piston valve 94 also has a sec- 0nd andmuch smaller land H5 which controls the admissionof-pressure fluid fromthe pressure passage H38 and bore llldto a second pluralitybi transverseports H5 in the sleeve valve- 96 which also extend from the periphery ofthe.

sleeve valve to the central sleeve bore )5.

The sleeve valve .63 hydraulically operatedby .a: difierential. areaarrangement which is showntmore clearly in Figures Sand 7.. Thedifferential iarea is ,provided..by.,.two floating pin sure port ii tothe left of the tank port l28,, and which is connected to thetransverse. ports holes llflconstructed in the sleeve and extending fromthe left end of the valve to the "transverseports H2; and four-floatingpinholes I20 extending fromthe right. end of the sleeve valve to thetransverse. ports H6. Two duplicate pins I22,

one of which is shown in Figure l, are floatablv mounted in the pinholes 1 58 while four duplicate pins I24, only one of which is shown inFig-.

ure l, are-floatably mounted inthe holes I20.

also limits leftward movement of' the valvefifi.

The right end of the valve. 96 is connected to tank: l2 by means of agroove l2? in the-end of the valve so connected to which is one end ofthe longitudinal passage 130, the latter of which is connected to thetank by means of bore I06;-

passagel iii; port Hid; and conduit H3. Thelefti end or" the'valve csisconnected to tank by means of the smaller portion of the bore I iiiposition shown.

the pressure fluid source and a forceequal tothe pressure times the endarea of the two pins is created to shift the valve 96 to the rightwardposition. with the piston valve 94, is adapted to connect the right endof the motor 86 either totank on to the pressure fluid source. In theposition of sage 126; one end of which constitutes the motor port i2,and the other end of which opens to the I28, constructed in the sleevevalve 536, leads di-v rectly to alongitudinal passage ltd extendingcompletely through the sleeve and which opens atone end to the smallerleft end section of the tank.

out of registry'with the passage 25 and a pres- HZ, moves into registrywith the passage I26 so as to disconnect the tank from and to connectthe pressure fluid source to the right end of the motor 65. The pistonvalve-dd is actuated by the motor 555 near each end of its stroke bymeans of two-dowel pins indicated by the .numerals I32- and 134 fastenedto the pinion gear 38 and ex.- tending therefrom, such pins beinglocated apart, which alternately contact a lever I36 fas-i tened to andextending from the piston valve,- 95. When the pins 132 and I34 loseoontact with the lever Ltd, the piston valve 94 is operated to andmaintained in the neutral position shown by. 5 means. of duplicatesprings #38 abutting each end of the valve,

Means for maintainin the. closed portion of:

thesystem comprising the conduit, 63 connected to, the-left end. of.motor iii and to-the right end; of, =motor .56.. and thus. insuringcompletion of The sleeve valve-96, in cooperation operation of themotors has been provided for by a duplicate check valve and passagearrangement which may be formed integrally with the motor 56. Referringto Figures 1, 9, and 10, the body of the motor 56, indicated by thenumeral I46, is provided with end caps I42 and I44 at opposite endsthereof which close the open ends of the longitudinal bore 60 withinwhich the piston 58 is mounted. The end caps I42 and I44 are spacedapart from the end faces of the motor body I40 by means of spacers I46and I48 having enlarged openings I50 and I52 (Figures 1 and 9) whichconnect the open ends of longitudinal passages I54 and I56 at theopposite ends of the motor body I40 to the opposite ends of thelongitudinal bore 60 within which the motor piston 58 is mounted. Thelongitudinal passage I54 is connected directly to the piston bore 60 byan angular passage I58 which is adapted to be closed by the piston 58except when the piston 58 has reached its complete rightward position.The longitudinal passage I56 is connected directly to the piston bore 60by an angular passage I60, the latter of which is adapted to be closedby the piston 58 except when the piston 58 has reached its completeleftward position. Mounted in the longitudinal passages I54 and I56 arecheck valves, indicated generally by the numerals I62 and I64, whichrespectively permit flow from the longitudinal passage I54 to the rightend of bore 60 and permit flow from the longitudinal passage I56 to theleft end of bore 60.

Only one of the check valve and passage arrangements associatedtherewith will be effective during operattion. The duplicate arrangementis provided in case of the reversal of connections to the opposite endsof the motor 56. When the connections of the motor 56 are reversed, thepistons of the motors will be simultaneously operated in oppositedirections. When the connections are as illustrated, the pistons will besimultaneously operated in the same direction.

If the connections to the motor 56 are as illustrated and the piston 58has completed a rightward directional movement, and the piston 68 of themotor 66 has not completed its rightward directional movement, pressurefluid is connected to the left end of the motor 66 in order to completethe rightward directional movement of the piston 68 by reason of theangular passage I58, longitudinal passage I54, and check valve I62. Ifthe connections to the motor 56 were reversed and the piston 58 hadcompleted a leftward directional movement and the piston 68 had notcompleted its rightward directional movement, the piston 68 of the motor66 will complete such movement because of the angular passage I60,longitudinal passage I56, and check valve I64. The duplicate auxiliarypassage and check valve arrangement is also utilized when priming thesystem in addition to insuring synchronized and complete movement of themotor pistons.

Referring to Figure l, in operation, with the parts in the positionshown and with the accumulator 28 filled with pressure fluid from thepump I and the delivery from the latter being by-passed through theunloading valve 24 to the tank I2, pressure fluid from the accumulator28 is delivered to the pressure port I8 of the rotary control valve bymeans of branch conduit 38 and pressure delivery conduit I6.

In the position shown, the pressure delivery port I8 of the controlvalve 20 is connected to the motor port 34 and the motor port 36 whilethe tank port 38 is blocked from communication with all other ports. Thecontrol valve mechanism comprising sleeve valve 96 and piston valve 94are in a position blocking the pressure passage I66 from the right endmotor port I2 and connecting the latter port to the tank port I08. The

pistons of the motors are at their intermediate stage of a rightwarddirectional movement. The pressure fluid source is connected to the leftend of the motor 56 by means of conduit 52, and although the pressurefluid source is connected by means of conduit III to the pressure portI04 of the valve mechanism of the motor 66, the pressure port I04 isclosed by such valve mechanism from communication with the right end ofmotor 66. As the piston 58 of the motor 56 is operated rightwardly,fluid displacement from th right end of the motor is delivered to theleft end of the motor 68 by conduit 63 and port 64 to operate the piston88 of the motor 66 rightwardly in unison with the piston 56 of the motor56. As the pistons are operated rightwardly the pinion gears 86 and 88are operated counterclockwise by reason of being in mesh with the pistongear racks 82 and 84. Thus, if windshield wiper blades, for example,were fastened to the shaft stems of th pinion gears, they would besimultaneously operated in a swinging are as the pinion gears wereactuated by the pistons.

Fluid displacement from the right end of the motor 66 is delivered tothe tank I2 by means of bore I0, port I2, passage I26, sleeve valve tankport I28, longitudinal passage I30, bore I00, passage IIO, tank portI80, and conduit II3. When the right end of the piston has passed overport 12 fluid displacement is enabled to leave the right end of the boreI8 by reason of the ports 83 in the hollow section SI of the piston 68.

As the piston 68 of the motor 66 nears a completion of a rightwarddirectional movement, the dowel pin I32 associated with the pinion gear88 comes in contact with the lever I36 and will actuate the piston valve84. When the piston valve 94 is shifted leftwardly, the land I I5thereof closes the ports I I6 from communication with the pressurepassage I06. A reaction force equal to pres sure times the end area ofthe two pins is created to shift the valve 96 rightwardly until abutmentwith the end plate I02. Fluid from the right end of the valve 96 isdirected to tank I2 by means of groove I21, longitudinal passage I30,bore I00, passage IIO, port I08, and conduit II3. When the sleeve valve96 is operated rightwardly, the tank port I28 thereof passes out ofregistry with the passage I26, and the pressure port I3I of the sleevevalve registers with the passage I26 to admit pressure fluid to theright end of the motor 66 by means of the port I2 and plurality ofpiston ports 83. The accumulator is then simultaneously connected to theright end of the motor 66 and to the left end of the motor 56 but due tothe larger pressure effective surface area I8 of the right end of thepiston 68, the piston 68 will be operated leftwardly and the fluiddisplacement from the left end of the motor 66 will be directed by port64 and conduit 63 to the right end of motor 56 to also shift the piston58 thereof leftwardly. Fluid displacement from the left end of the motor56 is added to the accumulator displacement to operate the motor 66. Thedisplacement from the left end of motor 56 is directed to the pressureport I04 of the valve mechanism controlling motor 66 by means of conduit52, port 34 of rotary control valve 20, radial passage 44, longitudinalpassage 43, port 36, and conduit III.

From the pressure port I94, pressure fluid is directed to the right endof the motor 66 by means of pressure passage 906, the transverse portsH2, port Hi, passage I25, port 12, and piston ports 83. When the piston68 has been operated leftwardly, a distance suiflcient to uncover theport 12, pressure fluid is admitted directly to the right end of bore itthrough the ports 12.

When the piston t3 nears the end of its leftward movement, the pin i3 lextending from the piniongear 88 will contact the lever i3 5, and thepiston valve 94 will be shifted to the right. When the piston valve M isshifted rightwardly, the pressure'port 1M and pressure passage ltd areconnected to the transverse ports 5 l2 and to the transverse ports H5.Because of the differential areaprovided by the two floating pins in theleft end of the sleeve valve 38 and the four floating pins in the rightend of the valve, the valve will be fluid operated to the left untilengagement with the shoulder i233. Fluid from the left end of valve 96is directed to tank l2 by means of bore I09, passage are, port 183, andconduit H3. The vale 96 is shifted leftwardly by the difference in forcecreated by the pressure times the end area of four pins minus thepressure times the end area of two pins. The pressure port it! of thevalve 96 will move out of registry with the pressure passage H6, and thetank port 523 move into registry with the pressure passage I25. thismanner the pressure fluid source is disconnected from the right end orthe motor 66 and the tank 52 connected thereto. As the pressure fluidsource is continuously connected to the left end of the motor 58, thepiston thereof is fluid opconducted from the left end of the bore of themotor 56 to the left end of the bore it of the motor 66 by way of theport 158, longitudinal passage 54, check valve I62, and the port 52 ofthe motor 55, the conduit 53, and port 6-; of the motor 66. completion.of their rightward movement when the connections to the motor 5% are asillustrated, or, if the connections to the motor 56 are reversed,stopped at the completion of a rightward movement of the motor and aleftward movement of the motor 86, by rotating the control valve piston45) counterclockwise to the operating position shown in Figure 1. Thiscomprises the motor stop position of the control valve is and places themotor port 36 into communication with the tank port 38 by means of theradial passage 4'6 and longitudinal passage 48, and places the motorport 34 in communication with the pressure port is by means of thetransverse passage :23 and radial passage id. Pressure fluid is then,instead of being connected to both of the motor ports 34 and 36, onlyconnected to the motor port 34 from whence it is delivered to the leftend of motor 55 'by means of the conduit 52 to shift the piston thereofto the right. Fluid displacement from the right end of the motor 58 isconducted by the conduit 63 to the left end of the motor 66 to operatethe piston 63 thereof also to the right.

If the control valve 20 is operated to the motor stop position, forexample, while the pistonsare The motors may he stopped at the 1 iii)'19 being actuated in a rightward direction such as is shown in Figure1, the pistons will continue their movement until completion. lhecontrol valve mechanism comprising the sleeve valve 96 and piston valve94 will be in the position shown, and fluid displacement from the rightend of the motor 66 is directed to tank by means of the port 12 andpassage I26, the sleeve valve tank port E25 and longitudinal passage539, bore )0, passage Ht, port Hi8, and conduit H53. If the controlvalve 2t is operated to the motor stop position while the pistons arebeing actuated in a leftward direction, the piston movements will bereversed to the rightward direction and their actuation to their stoppedposition will be as previously stated except that fluid displacementfrom the right end of the motor 56 will be conducted to the tank 12 bymeans of the motor port 12, passage I26, sleeve Valve pressure port I31,the transverse ports H2, pressure passage and pressure port use and E64,conduit ill, motor port 3%.; of control valve 23, the transverse ports46 and longitudinal passage 48 of piston 30, tank port 38, and conduit50.

Thus, regardless of the position of the motor pistons, when the controlvalve 2% is operated to the motor stop position, the right end of themotor 55 will be connected to the tank [2. When the control valvemechanism is in the position shown, the tank port its of the sleevevalve 95 will be in registry with the passage l25 and the fluiddisplacement from the right end of the motor 56 will be conducted to thetank via the control valve mechanism and conduits H3 and 5B. When thecontrol valve mechanism is in the opposite position shown, the sleevevalve pressure port it! will be connected to the passage H26, and fluiddisplacement from the right end of the motor will be conducted to thetank 42 via the control valve mechanism, conduit Hi, control valve 20,and conduit 58. This arrangement of stopping the motors simultaneouslyat the completion of one of their strokes is particularly suited to ahydraulic transmission for driving windshield wipers as the windshieldwipers may be automaticall actuated to what is conventionally known as aparked position rather than at, or to, an intermediate position of theirstroke.

In summary, the invention comprises a hydraulic transmission systemhaving two reversible fluid motors which are continuously andsimultaneously driven in reversing cycles. One end of one of the motorsis continuously connected to a pressure fluid source, which in this caseconstitutes an accumulator which is constantly filled with pressurefluid at a predetermined pressure by a fluid pump through thecooperation of an unloading valve. The other end of this motor isconnected by conduit means in a series or closed relationshi to thesmaller displacement end of the other reversible fluid motor. Theremaining end of the latter motor is controlled by automaticallyoperated valve mechanism so as to connect the port leading to such endor" the motor alternately to the pressure fluid source and to exhaust.Due to the larger pressure effective surface area of the piston providedin the motor controlled by the automatically operated valve mechanism,when the pressure fluid source is connected simultaneously to bothmotors, the motor having the piston with the larger-pressure effectivesurface area will be actuated and the displacement from the smaller endof such motor is utilized to operate the other motor. When the pressurefluid source is disconnected from the end of the motor with 11 thepiston having the larger pressure effective area and connected toexhaust instead, as the pressure fluid source is continuously connectedto one end of the other motor, such motor will be actuated in theopposite direction and the displacement from such motor is utilized toactuate the remaining motor also in the opposite direction.

The motors will be simultaneously, continuously operated in reversingcycles until the control valve is operated to the motor stop position atwhich time the motors will be actuated to the completion of one of theirstrokes, rather than stopping the motors at some intermediate stage oftheir strokes.

The speed of the motors may be selectively controlled by partially orfully opening the metering slot 53 of the manually operated controlvalve 20. When the motors are being operated in a rightward directionalmovement, pressure fluid from the accumulator is throttled over themetering slot 53 to the left end of the motor 56 in order to control thespeed of both motors. When the motors are being operated in a leftwarddirectional movement, pressure fluid from the accumulator is throttledover metering slot 53 to the right end of motor 66 in order to controlthe speed of both motors. Thus, the arrangement is such that a singlemanually operated control valve controls the speed of both motors inboth directions of operation. It should be noted also that control valvealso performs the function of controlling the starting and stopping ofboth motors.

While the form of embodiment of the invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. In a hydraulic power transmission system for driving a pair of loaddevices in unison and in continuous reversing cycles the combination ofa pressure fluid source, a pair of reversible fluid motors adapted to beseparately associated with the load devices for driving the same, eachof said motors including two ports which alternate as inlet and outletports and one of said motors having a different fluid displacement in atleast one direction of operation from the displacement of the othermotor in either direction of operation, means hydraulically connectingone of the ports of said other of the motors contin ously to thepressure fluid source and the other port of said other motor to one ofthe ports of said one motor, and automatically operated control valvemeans alternately connecting the remaining port of the said one motor tothe pressure fluid source and to exhaust.

2. In a hydraulic power transmission system for driving a pair of loaddevices in unison and in continuous reversing cycles the combination ofa pressure fluid source, a pair of reversible fluid motors adapted to beseparately associated with the load devices for driving the same, eachof said motors including two ports which alternate as inlet and outletports and one of said motors having a different fluid displacement in atleast one direction of operation from the displacement of the othermotor in either direction of operation, means hydraulically connectingone of the ports of said other of the motors continuously to thepressure fluid source and the other port of said other motor to one ofthe ports of said one motor, and control valve means hydraulicallyconnected to the remaining port of said one motor and operated by one ofsaid pair of motors after a predetermined operational movement in eachdirection thereof for alternately connecting the remaining port of saidone motor to the pressure fluid source and to exhaust.

3. In a hydraulic power transmission system for driving a pair of loaddevices in unison and in continuous reversing cycles the combination ofa pressure fluid source, a pair of reversible fluid motors adapted to beseparately associated with the load devices for driving the same, eachof said motors including two ports which alternate as inlet and outletports and one of said motors having a different fluid displacement in atleast one direction of operation from the displacement of the othermotor in either direction of operation, means hydraulically connectingone of the ports of said other of the motors continuously to thepressure fluid source and the other port of said other motor to one ofthe ports of said one motor, two position control valve means forconnecting the remaining port of said one motor alternately to thepressure fluid source and to exhaust, and means associated with themotor having the different fluid displacement in one direction ofoperation automatically operating the control valve means from oneposition to another after a predetermined operational movement of themotors in both directions.

4. In a hydraulic power transmission system for driving a pair of loaddevices in unison and in continuous reversing cycles, the combination ofa pressure fluid source, a pair of reversible fluid motors adapted toseparately drive the load de vices, said motors being of the cylinderand piston type having two ports for alternately admitting andexhausting fluid from opposite sides of the piston for operating thesame, the piston of one of said motors having at least one largerpressure effective surface area exposed to pressure fluid entering theport on that side of the piston than one of the pressure effectivesurface areas of the piston of the other motor, hydraulic conduit meanscontinuously connecting the pressure fluid source to a port of saidother motors and the other port of said other motor to a port of thesaid one motor, and control valve means automatically connecting theremaining port of the said one motor alternately to the pressure fluidsource and to exhaust after a predetermined operational movement of themotors in both directions.

5. In a hydraulic power transmission system for driving a pair of loaddevices in unison and in continuous reversing cycles, the combination ofa pressure fluid source, a pair of reversible fluid motors adapted toseparately drive the load devices, said motors being of the cylinder andpiston type having two ports for alternately admitting and exhaustingfluid from opposite sides of the piston for operatingthe same, thepiston of one of said motors having at least one larger pressureeffective surface area exposed to pressure fluid entering the portonthat side of the piston than one of the pressure effective surfaceareas of the piston of the other motor, hydraulic conduit meanscontinuously connecting the pressure fluid source to a port of saidother motor and the other port of said other motor to a port of the saidone motor, two position control valve means for connecting the remainingport of the said one motor alternately to the pressure fluid source andto exhaust, and means associated with the motor having the piston withthe larger pressure'effec tive surface area automatically operating thecon trol valve from one position to another after a predeterminedoperational movement of the motors in both directions.

6. In a hydraulic power transmission system for driving a pair of loaddevices in unison and in continuous reversing cycles, the combination ofa first and a second reversible fluid motor, each of which has two portswhich alternate as inlet and outlet ports and the first motor having adifferent fluid displacement in one direction of operation from theother motor in the opposite direction. of operation, means continuouslyhydraulically connecting the pressure fluid source to a port of thesecond motor and the other port of said motor to a port of the firstmotor, control valve means for connecting the remaining port of thefirst motor alternately to the pressure fluid source and to exhaust,means for automatically operating the control valve means after apredetermined operational movement of the motors in each direction forcausing simultaneous operation of and continuous reversing cycles of themotors, and control means for selectively stopping the motors byconnecting the remaining port of the first motor to exhaust.

7. In a hydraulic power transmission system for driving a pair of loaddevices in unison and in continuous reversing cycles, the combination ofa first and a second reversible fluid motor, both of which are of thetype having a reciprocating piston and two ports which alternate asinlet and outlet ports for the admission and exhaust of fluid to andfrom opposite sides of the piston for operating the same, and the firstmotor having a different displacement in one direction of operation fromthe other motor in the opposite direction of operation, means forming acircuit continuously connecting the pressure fluid source to a port ofthe second motor and the other port of said motor to a port of the firstmotor, control valve means for connecting the remaining port of thefirst motor alternately to the pressure fluid source and to exhaust,means for automatically operating the control valve means at the ends ofthe motor strokes for causin simultaneous operation of the motors and incontinuous reversing cycles, and control means for selectively stoppingthe motors at one end of their piston stroke by connecting the remainingport of the first motor to exhaust.

8. In a hydraulic power transmission system for driving a pair of loaddevices in unison and in continuous reversing cycles, the combination ofa pressure fluid source, a pair of reversible fluid motors adapted to beseparately associated with the load devices for driving the same, eachof said motors including two ports which alternate as inlet and outletports, said motors having different displacements in at least onedirection of their operation, means continuously connecting the pressurefluid source to one of the ports of one of the motors and the other portof said motor to one of the ports of the other motor, automaticallyoperated control valve means alternately connecting the remaining portof the other motor to the pressure fluid source and to exhaust, and asingle manually operated control valve for selectively starting,stopping, and controlling the speed of the motors.

9. In a hydraulic power transmission system for driving a pair of loaddevices in unison and in continuous reversing cycles, the combination ofa pressure fluid source, a pair of reversible fluid motors adapted to beseparately associated with the load devices for driving the same, eachof said motors including two ports which alternate as inlet and outletports, said motors having difierent displacements in at least onedirection of their operation, means continuously connecting the pressurefluid source to one of the ports of one of the motors and the other portof said motor to one of the ports of the other motor, automaticallyoperated control valve means alternately connecting the remaining portof the other motor to the pressure fluid source and to exhaust, and asingle manually operated control valve for selectively controlling thespeed of the motors in both directions of operation.

10. In a hydraulic power transmission system for driving a pair of loaddevices in unison and in continuous reversing cycles, the combination ofa pressure fluid source, a pair of reversible fluid motors adapted to beseparately associated with the load devices for driving the same, eachof said motors including two ports which alternate as inlet and outletports, said motors having different displacements in at least onedirection of their operation, means continuously connecting the pressurefluid source to one of the ports of one of the motors and the other portof said motor to one of the ports of the other motor, automaticallyoperated control valve means alternately connecting the remaining portof the other motor to the pressure fluid source and to exhaust, and asingle manually operated control valve selectively controlling the flowof fluid to one of the motors for controlling the speed of both motorsin one direction of their operation and controlling the flow of fluid tothe other of said motors for controlling the speed of both motors intheir opposite direction of opera.- tion.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 500,580 Mason July 4, 1893 2,105,473 Dean Jan. 18, 19382,446,611 Rose Aug. 10, 1948 FOREIGN PATENTS Number Country Date 36,829Germany Mar. 11, 1886

